<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>placeholder 属性</title>
</head>
<body>

<form action="/example/html5/demo_form.asp" method="get">
  <input type="search" name="user_search" placeholder="Search W3School" />
  <input type="submit" />
</form>

</body>
</html>